Beefy set off from Hotel du Vin in Cambridge city centre to Royston joined by friend and Olympic athlete Daley Thompson and racing legend Bob Champion.

He was due to be joined by more than 200 people for the final four miles to Royston.

The Cambridgeshire stretch is the ninth leg of Beefy’s Great British Walk in aid of Leukaemia and Lymphoma Research.

He said: “I’ve been doing these walks for 27 years and this is the 14thone. When we started there was a 20 per cent chance of surviving leukaemia, this is now between 92 and 93 per cent.

“One of the biggest kicks is when you get people coming up to you who are now adults who said they survived the disease.

“They tell you ‘I made a full recovery’ and are so pleased with the work we do. It’s nice to give something back and luckily with my sporting career I’m in the position to do that.”

This will be the sporting hero’s 14th charity walk to beat blood cancer and in the last 16 years he has raised £12 million for the charity, of which he is now president.

The family of 6-year-old leukaemia survivor Charlotte Parr, from Steeple Morden, were among the hundreds of people to walk with Sir Ian from Wimpole.

Charlotte was diagnosed with a rare form of blood cancer in the summer of 2008 when she was just 3.

Her father Karl said: “It’s really important that the message gets out there because there’s lots of research that needs to be done. Having a high profile person doing the walk means we get a fantastic following.

“This is part of a national awareness campaign and we’re more than happy to do our bit to keep raising awareness locally and showing Sir Ian that his work is helping.

“This walk in particular is all about families joining in and this whole experience for us has been about family, so it’s particularly poignant.”